Local Climatological Data Summary Aurora, Illinois

SWS Miscellaneous Publication 98-15 STATE OF ILLINOIS DEPARTMENT OF NATURAL RESOURCES Local Climatological Data Summary Aurora, Illinois 1901-1996 Herbert Hoffman 1, Audrey A. Bryan 2 and Wayne Wendland 2 1 2 National Weather Service, Romeoville, IL Illinois State Water Survey, Champaign, IL Illinois State Water Survey 1996

Climatological Summary: LOCAL CLIMATOLOGICAL DATA FOR AURORA ILLINOIS 1901-1994 Aurora (Kane County) has a temperate continental climate, dominated by maritime tropical air from the Gulf of Mexico from about March through November. Gulf air generally supports relative humidities of about 60% during the day and 85% at night. This is the air mass which yields a "muggy" environment, particularly during June through August. During these months, there are occasional, brief interruptions of drier, cooler air from the Pacific Ocean, but they typically only last for a few days. From November through March, the Aurora area is dominated by Pacific Ocean air. However, four to six times each winter, cold, dry air from the Canadian Arctic breaks south, bringing temperatures into negative values. The highest temperature on record is 111ºF recorded 14 July 1936, whereas the lowest is -26 F occurring on 20 January 1985. Winter winds are generally out of the west or northwest. The greatest precipitation amount ever recorded in Aurora in 24 hours was 10.48 inches on 10 October 1954. The greatest monthly total ever was 14.86 inches, also occurring in October 1954. Summer day temperatures in north-central Illinois are usually in the 80s, occasionally in the 90s, with nighttime lows about 18 F lower. Humidities are relatively high, and comfort is often impaired. Average annual precipitation is 36.88 inches. Each summer month generally supports some 4 inches of rainfall, mostly in showers and thunderstorms are sometimes accompanied by hail. Past tornadoes were infrequent. Summer winds are usually out of the southwest. Winters in northern Illinois can be severe, representing a distinct cold season with frequent frost, and snowfall. Arctic air from Canada frequently dominates northern Illinois in winter. Even tropical air from the Gulf is cooled somewhat on its northward tack. Average January highs are near 30 with lows near 10. Ground frost is common from January through March. Average annual snowfall is about 30 inches but there is a great deal of variability. Snowfalls of 6 inches or more at Aurora are expected about once every other year on average, although three such storms occurred during January 1918. The greatest snowfall ever during one month in Aurora was 36.4 inches in December 1951. Snowcover often continues in Aurora for a few weeks at a time. The longest snowcover of at least two inches in Aurora was 111 days during the 1978-79 winter.

Latitude N41 45 Longitude W88 29 Clinatological Sunnary Beans : 1961-1990 ; Extrenes : 1901-1995 Aurora, IL Elevation 640 Teoperature Degree Days Precipitation Snow Means Extrenes Number of Days Greatest Greatest Greatest Greatest Ave Ave Ave High Low Max Min Monthly Daily+ Monthly Snow Mon Max Min Mean Tenp Date Tenp Date >=90 <=32 <=32 <=0 Heat Cool Grow Mean Anount Year Anount Date >=0.1 >=0.5 >=1.0 Mean Anount Tear Depth Date Jan 28.7 10.7 19.7 66 23/1909* -26 20/1985 0 15 29 6 1,354 0 0 1.56 4.80 1916 2.91 12/1960 5 1 0 8.6 32.0 1918 25 28/1979/ Feb 33.6 14.8 24.2 70 28/1976-25 13/1905* 0 11 26 4 1,118 0 0 1.34 3.86 1908 1.80 22/1913 4 1 0 7.6 23.6 1908 26 12/1979/ Mar 45.7 26.9 36.3 83 29/1986* -15 8/1943 0 4 22 0 871 0 19 2.57 6.12 1920 3.51 19/1948 6 2 0 3.7 15.4 1972 19 1/1979 Apr 59.6 37.5 48.6 92 11/1930 8 7/1982 0 0 9 0 478 7 98 3.83 8.38 1909 3.52 28/1959 7 2 1 1.1 13.0 1938 9 3/1975 Hay 71.3 47.5 59.4 104 31/1934 21 10/1966 1 0 1 0 213 51 321 3.78 8.62 1915 3.59 10/1990 7 3 1 0.0 1.3 1907 Jun 81.0 57.2 69.1 106 1/1934 34 4/1929 4 0 0 0 37 163 577 4.25 13.19 1902 4.38 24/1994 7 3 1 0.0 Jul 84.2 61.8 73.1 111 14/1936 40 3/1907 8 0 0 0 6 259 717 4.11 9.60 1915 6.17 2/1983 6 2 1 0.0 Aug 82.0 59.8 70.9 105 9/1934 37 31/1915 5 0 0 0 13 204 649 3.86 14.49 1972 7.12 26/1972 6 2 1 0.0 Sep 75.1 52.0 63.6 103 14/1939* 25 26/1928* 2 0 1 0 114 82 409 3.84 10.97 1961 6.10 13A978 6 2 1 0.0 0.2 1942 Oct 63.3 40.4 51.9 90 3/1954* 11 28/1925* 0 0 6 0 409 11 150 2.49 14.86 1954 10.48 10/1954 5 2 1 0.2 3.9 1967 2 26/1967* Nov 48.0 29.9 38.9 81 1/1950-11 30/1947 0 2 19 0 761 0 24 2.82 7.89 1985 2.74 11/1995 5 2 1 1.2 8.1 1955 5 7/1951/ Dec 33.7 17.2 25.5 67 2/1982-25 26/1914 0 11 27 3 1,189 0 1 2.43 6.31 1949 2.83 3/1982 5 1 0 8.2 36.4 1951 31 25/1951/ Tot/Ave 58.8 38.0 48.4-20 43 140 13 6,563 777 2,965 36.88 69 23 8 30.6 * Becords also occurred on following dates: + Calendar Day. Jan: High Tanp 1/31/1989 / Becords also occurred on following dates Feb: Low Tenp 2/21/1951 Jan: Snowdepth 1/31/1979 Mar: High Tenp 3/31/1986 Feb: Snowdepth 2/13A979,2/19/1979, 2/20/1979 Sep: High Tenp 9/15/1939 Oct: Snowdepth 10/27/1967 Low Tenp 9/28/1942 Nov: SNowdepth 11/8/1951, 11/28/1977, 11/29/1977, 11/30/1977 Oct: High Tenp 10/6/1963 and 10/1/1971 Dec: SNowdepth 12/26/1951 Low Tenp 10/29/1925 and 10/29/1952 Probabilities: Precipitation (in) Missing Data: 3.0% Station: (110338) AURORA_COLLEGE Years: 1961 To 1990 1% 5% 10% 25% 50% 75% 90% 95% 99% Ja 0.09 0.24 0.37 0.71 1.28 2.11 3.10 3.81 5.40 Fe 0.00 0.23 0.41 0.73 1.20 1.80 2.48 2.95 3.98 Ma 0.44 0.79 1.03 1.56 2.34 3.35 4.47 5.24 6.90 Ap 0.97 1.50 1.86 2.60 3.63 4.90 6.26 7.19 9.14 Ma 0.87 1.40 1.76 2.49 3.54 4.84 6.25 7.21 9.24 Jn 1.21 1.79 2.17 2.93 3.97 5.22 6.56 7.45 9.32 Ju 1.17 1.74 2.11 2.85 3.87 5.11 6.43 7.31 9.16 Au 0.23 0.61 0.95 1.80 3.26 5.39 7.93 9.75 13.83 Se 0.00 0.00 1.02 1.90 3.18 4.87 6.79 8.13 11.07 Oc 0.27 0.55 0.78 1.29 2.11 3.21 4.49 5.38 7.34 No 0.45 0.82 1.09 1.69 2.57 3.73 5.03 5.92 7.86 De 0.30 0.60 0.83 1.36 2.17 3.25 4.49 5.36 7.25 An 21.45 25.69 28.22 31.56 35.57 39.91 44.10 46.74 51.97 Wi 1.60 2.34 2.83 3.79 5.09 6.66 8.33 9.44 11.78 Sp 4.14 5.46 6.27 7.80 9.79 12.08 14.43 15.97 19.12 Su 4.99 6.52 7.46 9.23 11.52 14.15 16.83 18.58 22.17 Fa 3.20 4.40 5.16 6.63 8.57 10.86 13.24 14.81 18.06 Growing Season Summary Station: (110338) AURORA_COLLEGE Years: 1961 To 1990 Missing Data: 3.5% Base Date of Last Spring Occurrence Date of First Fall Occurrence Temp Median Early 90% 10% Late #yrs Median Early 10% 90% Late #yrs 32 5/03 3/28 4/09 5/19 5/29 29 10/08 9/22 10/01 10/23 10/29 29 30 4/24 3/28 4/08 5/09 5/12 29 10/14 9/24 10/02 11/03 11/13 29 28 4/10 3/27 4/03 5/01 5/10 29 10/22 10/02 10/06 11/15 11/17 29 24 4/07 3/19 3/24 4/21 5/10 30 11/03 10/02 10/20 11/15 11/20 29 20 3/24 2/23 3/12 4/07 4/10 30 11/14 10/02 10/28 11/26 12/04 29 16 3/18 2/07 2/19 4/04 4/09 30 11/28 10/26 11/08 12/08 1/03 29 Base Length Of Season (Days) Temp Median Shortest 10% 90% Longest #yrs 32 160 128 139 185 196 28 30 176 140 150 198 208 28 28 194 150 170 214 225 28 24 212 173 184 229 240 29 20 232 191 211 257 269 29 16 251 222 228 291 303 29 3

AVERAGE MAXIMUM TEMPERATURE ( F) AURORA, IL YEAR JAN FEB MAR APR MAY JUN JUL AUG SEP OCT NOV DEC ANN 1901 32.1 24.8 42.2 59.8 71.2 85.9 94.6 84.3 76.8 67.4 46.3 30.1 59.6 1902 32.7 29.0 48.5 60.7 73.4 76.2 83.5 78.2 69.7 63.5 53.8 31.3 58.4 1903 30.7 31.6 50.6 60.2 73.7 75.7 84.2 78.7 73.7 61.9 44.8 28.1 57.8 1904 23.8 26.0 43.4 53.4 71.4 79.6 83.2 78.5 73.4 62.1 51.3 33.1 56.6 1905 25.8 24.9 49.9 59.0 69.8 80.2 81.5 83.1 76.2 61.7 48.9 36.9 58.2 1906 37.3 34.6 35.2 63.3 72.5 80.5 84.9 85.5 78.2 60.5 45.8 36.8 59.6 1907 33.9 34.2 52.2 50.4 64.1 76.7 82.4 79.5 71.1 59.1 46.6 36.6 57.2 1908 34.4 31.6 48.5 60.5 69.7 78.8 83.8 82.4 80.5 64.2 51.0 36.8 60.2 1909 34.7 39.0 42.5 55.0 68.9 77.8 82.0 84.9 71.8 58.4 56.2 25.5 58.1 1910 29.5 30.8 59.5 63.0 65.0 81.5 88.2 83.4 72.2 66.2 41.8 30.2 59.3 1911 34.8 37.8 48.6 55.5 78.0 83.4 85.9 80.4 74.4 58.9 41.9 38.5 59.9 1912 16.5 26.6 35.4 60.0 72.0 77.9 82.9 78.5 74.6 63.6 49.8 39.9 56.5 1913 34. 9 1 31.7 43.7 62.4 69.8 83.5 86.4 83.7 74.2 60.4 53.9 40.7 60.4 1914 36.8 25.8 44.1 61.6 73.5 80.2 87.0 84.1 73.8 66.5 52.0 28.4 59.5 1915 27.1 38.9 41.6 69.2 64.9 76.0 78.8 74.6 74.3 64.9 50.7 31.7 57.7 1916 35.0 30.1 42.5 59.0 70.9 72.9 91.0 87.3 73.2 62.7 49.8 31.6 58.8 1917 29.8 27.0 47.1 55.1 64.5 74.8 82.7 79.8 71.3 51.1 48.8 27.3 55.0 1918 17.6 34.5 53.7 54.2 76.0 79.2 82.1 84.8 67.4 65.1 48.4 39.2 58.5 1919 34.6 36.6 47.3 59.3 67.9 83.0 88.9 83.0 77.9 64.9 44.1 25.4 59.4 1920 24.2 1 32.3 48.9 52.2 68.5 80.2 83.4 81.2 77.7 69.6 45.9 37.1 58.4 1921 37.5 38.6 57.1 65.1 74.8 85.5 92.5 81.9 77.7 62.9 44.7 36.7 62.9 1922 32.6 37.8 46.6 59.2 75.3 82.7 83.3 84.4 79.4 66.6 49.7 36.3 61.2 1923 35.2 28.8 41.5 59.6 70.3 82.6 86.6 80.4 73.4 59.7 48.5 43.8 59.2 1924 27.1 33.1 39.0 58.6 65.1 75.4 80.2 79.0 67.1 69.0 49.7 29.2 56.1 1925 30.6 39.2 50.2 67.1 68.9 82.0 83.7 85.3 79.3 51.1 45.6 30.1 59.4 1926 33.9 36.3 39.0 53.7 73.9 76.1 82.8 82.7 71.0 59.1 43.1 32.1 57.0 1927 30.3 41.4 50.0 57.8 67.1 75.7 84.2 78.6 79.4 67.7 51.2 34.4 59.8 1928 32.8 37.9 47.2 56.6 73.8 76.1 84.7 84.4 73.2 65.5 48.2 38.4 59.9 1929 26.5 29.2 53.1 61.0 68.9 77.4 85.1 82.0 75.4 60.1 43.6 33.7 58.0 1930 26.4 45.9 46.5 63.0 71.1 79.5 87.0 84.5 76.3 59.9 50.6 35.2 60.5 1931 36.7 42.7 43.7 2 63.1 68.0 83.8 89.0 85.6 81.0 66.1 56.4 42.1 63.2 1932 37.9 42.6 37.3 59.4 73.7 82.8 87.6 85.2 75.2 61.9 44.9 36.5 2 60.4 1933 43.2 34.9 43.5 58.0 70.1 90.5 87.8 83.6 81.6 62.2 48.0 37.2 61.7 1934 37.5 31.1 42.1 63.5 81.7 87.7 90.0 83.2 72.8 66.4 52.4 30.8 61.6 1935 32.3 34.7 51.3 56.1 63.3 76.2 88.8 83.7 77.2 63.9 45.2 30.6 58.6 1936 24.8 22.3 49.1 56.6 77.6 81.8 96.4 89.8 76.8 62.6 45.7 40.4 60.3 1937 33.4 33.7 41.6 57.0 72.0 78.6 88.2 89.8 76.7 60.0 47.3 31.6 59.2 1938 31.5 40.6 54.2 60.3 71.1 78.3 85.7 87.0 75.4 70.1 53.2 36.3 62.0 1939 37.3 35.2 49.5 56.3 76.8 82.3 86.8 84.9 84.6 66.2 48.8 41.9 62.6 1940 23.1 34.9 39.8 57.5 66.2 80.5 88.2 83.8 77.0 68.4 47.1 39.2 58.8 4

AVERAGE MAXIMUM TEMPERATURE ( F) AURORA, IL YEAR JAN FEB MAR APR MAY JUN JUL AUG SEP OCT NOV DEC ANN 1941 34.5 33.3 41.7 65.6 77.1 80.4 85.8 85.2 79.8 64.1 50.4 41.2 61.6 1942 32.4 31.4 49.2 66.5 71.8 80.6 85.6 82.1 72.4 63.7 50.5 29.9 59.7 1943 31.2 37.6 43.1 57.6 66.2 82.8 86.3 84.2 71.8 64.0 43.3 36.1 58.7 1944 40.8 36.3 40.1 55.7 75.3 83.5 87.0 86.3 77.1 65.8 49.9 29.2 60.6 1945 26.0 34.9 60.7 60.4 65.3 77.0 83.3 82.9 72.5 62.2 47.6 27.4 58.4 1946 34.3 37.5 57.9 64.1 68.4 79.1 86.2 80.8 78.1 71.4 50.8 40.3 62.4 1947 35.8 27.5 39.7 58.8 66.5 78.1 82.7 90.6 76.8 73.1 41.9 37.8 59.1 1948 27.7 34.8 45.7 65.0 68.0 79.1 84.6 84.1 77.4 62.1 50.2 36.9 59.6 1949 34.2 34.0 46.0 60.1 73.2 85.0 87.6 84.9 70.9 68.7 50.1 39.6 61.2 1950 39.6 33.1 40.4 51.9 72.3 79.0 83.1 80.4 73.9 69.1 42.3 26.4 57.6 1951 29.5 33.8 43.1 56.4 73.6 76.6 82.7 79.2 72.0 65.1 40.8 33.0 57.2 1952 34.5 39.1 42.4 62.8 69.4 83.5 86.0 81.6 76.8 60.8 51.7 36.4 60.4 1953 34.1 40.1 46.4 55.9 71.6 84.2 85.7 86.0 79.0 71.1 52.2 37.9 62.0 1954 34.1 44.6 42.9 63.5 67.3 84.3 85.7 80.5 78.6 62.7 49.2 35.8 60.8 1955 30.5 34.6 46.9 67.8 74.4 77.2 89.4 86.7 78.3 65.5 44.3 33.0 60.7 1956 34.7 35.5 45.6 59.6 72.3 84.4 81.4 82.9 78.0 72.9 49.2 37.8 61.2 1957 26.0 39.5 46.0 58.8 68.2 79.9 85.3 82.6 73.8 61.4 47.6 41.2 59.2 1958 30.0 26.1 43.3 61.2 74.5 73.9 80.8 83.6 76.2 68.4 51.8 28.6 58.2 1959 25.5 32.3 46.4 59.8 75.7 83.1 84.4 85.9 77.9 58.4 40.6 41.1 59.3 1960 32.7 30.7 33.0 63.1 68.2 77.4 83.0 83.2 78.1 65.2 50.5 33.1 2 58.2 1961 30.5 41.3 48.1 53.5 68.0 81.0 82.2 82.7 77.7 64.1 48.1 32.3 59.1 1962 24.0 32.4 40.6 60.4 76.6 82.4 79.7 84.5 74.5 66.5 49.9 32.1 58.6 1963 19.8 27.5 49.9 63.7 69.7 83.9 84.1 80.9 76.6 75.3 53.4 24.6 59.1 1964 37.0 36.5 45.2 60.8 76.5 83.4 84.5 80.8 75.8 62.9 52.6 32.6 60.7 1965 31.3 33.8 35.1 57.4 76.2 81.1 84.5 78.8 72.4 63.1 50.0 41.4 58.8 1966 24.6 34.4 47.9 54.9 65.3 81.4 87.8 80.6 73.8 62.7 49.7 32.5 58.0 1967 34.8 28.0 45.4 59.9 65.8 81.7 81.2 78.7 74.7 60.7 42.9 36.3 57.5 1968 29.8 32.6 53.0 62.6 67.5 81.4 83.5 83.7 75.8 64.5 46.1 34.1 59.6 1969 27.3 35.2 44.0 61.9 70.9 75.5 83.1 84.6 75.1 61.6 45.2 32.8 58.1 1970 21.3 33.4 41.8 60.6 73.7 81.0 86.5 83.9 76.7 64.5 46.0 37.3 58.9 1971 26.2 34.4 42.1 60.7 71.2 87.2 82.7 83.7 80.1 71.8 50.1 40.5 60.9 1972 28.5 32.6 43.2 56.5 74.3 78.5 82.8 81.4 74.7 60.1 42.9 31.5 57.3 1973 36.0 35.3 52.9 58.3 66.8 82.6 86.4 85.6 75.9 68.6 50.1 35.1 61.1 1974 30.9 35.9 46.4 62.9 67.6 77.3 86.7 81.4 73.9 66.3 50.1 35.9 59.6 1975 36.6 34.1 43.4 56.6 78.6 82.7 1 84.2 83.9 71.3 67.4 55.0 35.5 60.8 1976 26.2 42.7 49.0 62.7 67.3 82.4 86.1 81.5 74.6 57.5 41.0 27.8 58.2 1977 17.6 34.0 51.7 67.0 80.1 79.9 86.2 79.5 73.3 60.7 47.0 30.5 59.0 1978 23.3 25.9 40.4 60.2 68.9 78.6 79.5 81.5 81.0 61.5 48.3 31.9 56.8 1979 19.7 23.5 44.0 54.4 72.1 80.9 82.7 79.9 75.4 1 59.5 1 45.7 1 37.7 1 56.3 1980 28.5 1 27.3 1 38.2 1 54.3 1 73.8 78.9 86.5 83.5 73.2 1 59.1 48.4 32.1 1 57.0 5

AVERAGE MAXIMUM TEMPERATURE ( F) AURORA, IL YEAR JAN FEB MAR APR MAY JUN JUL AUG SEP OCT NOV DEC ANN 1981 31.7 37.0 49.4 63.2 67.7 80.6 81.0 80.5 72.7 60.5 49.5 32.8 58.9 1982 22.3 30.6 43.3 55.6 77.1 76.7 84.2 79.8 73.6 66.3 47.3 42.5 58.3 1983 33.0 38.6 46.8 53.8 65.9 82.5 89.9 87.7 76.6 63.4 50.1 21.7 59.2 1984 26.4 42.4 36.8 56.6 68.5 82.8 83.2 86.8 74.1 66.2 2 49.9 2 39.3 2 59.4 1985 24.4 29.3 49.2 64.5 74.6 78.0 83.9 79.8 75.9 63.3 44.3 26.9 57.9 1986 32.0 30.9 51.1 65.3 71.9 79.7 85.7 78.l 1 54.1 1 62.4 3 43.6 3 35.4 3 44.9 1987 31.8 42.5 50.8 63.0 76.8 83.9 84.8 2 80.9 75.3 58.2 51.3 37.8 43.4 1988 28.4 31.8 47.9 60.2 77.3 86.5 90.6 87.5 78.8 57.5 49.2 37.3 61.1 1989 40.3 28.6 46.1 59.1 70.8 80.0 85.1 81.4 73.3 65.3 46.7 25.1 58.5 1990 41.6 39.8 49.8 58.4 1 67.0 81.6 81.7 81.4 76.8 63.7 53.6 36.2 41.6 1991 29.4 38.7 50.0 63.8 78.6 86.4 88.6 86.3 76.5 63.5 43.6 38.1 62.0 1992 35.2 40.0 47.8 57.0 71.7 80.1 79.8 78.1 73.0 61.8 43.6 34.2 58.5 1993 33.6 32.0 39.5 1 55.7 73.1 78.2 83.5 81.9 68.1 61.2 45.9 34.8 40.2 1994 23.0 31.1 48.1 62.5 72.6 83.3 82.8 78.3 76.4 64.2 51.9 40.7 59.6 1995 30.1 34.0 50.4 56.9 69.0 83.2 87.2 88.2 73.5 64.4 41.0 33.3 59.3 ----- 1 Elgin data substituted for Aurora 2 De Kalb data substituted for Aurora 3 Chicago-O'Hare data substituted for Aurora AVERAGE MINIMUM TEMPERATURE ( F) AURORA, IL YEAR JAN FEB MAR APR MAY JUN JUL AUG SEP OCT NOV DEC ANN 1901 15.7 3.5 26.1 35.9 46.2 58.2 65.3 60.2 50.9 40.7 24.6 15.7 36.9 1902 13.9 7.2 30.6 34.0 50.7 55.9 63.1 57.9 49.4 43.0 38.2 17.9 38.5 1903 15.3 14.4 31.6 37.8 49.8 51.0 60.6 58.4 50.5 39.9 26.0 7.5 36.9 1904 6.4 7.3 27.2 31.8 46.7 54.3 58.4 54.3 52.5 40.7 29.2 16.1 35.4 1905 9.2 6.3 30.7 36.5 47.5 55.8 59.5 60.4 53.2 38.3 27.4 20.4 37.1 1906 21.0 16.6 22.1 38.2 47.4 55.1 57.4 62.5 55.1 42.0 29.9 21.7 39.1 1907 16.0 15.2 32.5 30.4 40.7 54.3 61.3 57.5 51.7 37.5 26.5 22.1 37.2 1908 16.6 16.4 29.6 38.4 49.4 56.3 61.1 56.6 53.5 39.9 28.0 18.5 38.7 1909 18.0 21.2 26.8 35.5 45.0 56.1 58.7 61.5 50.1 35.4 37.0 9.7 37.9 1910 13.6 12.2 33.9 37.8 42.6 53.4 61.7 58.9 52.1 42.3 24.8 14.7 37.4 1911 16.3 22.7 26.3 36.6 51.6 59.1 60.1 58.2 55.0 41.0 25.1 23.9 39.7 1912 1.4 12.0 17.1 37.7 48.2 52.9 61.7 58.7 54.4 39.7 30.7 23.1 36.5 1913 17.5 1 13.5 22.6 36.8 47.2 56.3 61.6 61.2 50.9 41.5 36.8 27.7 39.5 1914 23.8 7.1 25.6 38.4 49.1 56.6 61.0 58.9 52.1 44.5 29.8 12.4 38.3 1915 9.1 26.2 24.2 43.3 44.3 52.9 58.5 55.0 54.1 41.4 31.7 18.7 38.3 1916 17.4 13.6 22.8 36.6 47.9 52.1 64.3 60.2 48.9 38.6 30.1 11.9 37.0 1917 10.3 8.1 27.7 35.3 40.6 52.6 60.6 56.4 49.2 32.7 31.1 10.0 34.6 1918-0.7 14.6 28.4 34.3 51.5 55.5 57.4 62.8 44.6 41.4 32.5 27.4 37.5 6

AVERAGE MINIMUM TEMPERATURE ( F) AURORA, IL YEAR JAN FEB MAR APR MAY JUN JUL AUG SEP OCT NOV DEC ANN 1919 17.9 19.7 27.8 38.3 44.1 61.7 62.8 58.9 54.0 44.1 28.2 9.8 39.0 1920 7.9 1 17.0 27.6 33.1 45.3 56.7 57.9 59.0 55.9 46.4 29.6 22.5 38.2 1921 22.6 24.7 34.0 40.8 51.2 66.5 70.5 62.8 56.8 41.7 31.1 21.8 43.7 1922 12.5 18.2 30.9 38.8 53.2 58.2 63.3 63.7 55.6 43.7 35.1 18.6 41.0 1923 21.3 11.3 21.6 35.2 46.5 61.8 64.1 58.8 53.7 37.6 32.0 28.5 39.4 1924 6.8 19.6 27.6 37.0 41.4 54.5 56.7 59.0 48.0 43.0 29.4 11.2 36.2 1925 11.8 21.1 26.9 41.0 41.1 58.5 60.2 59.0 58.3 34.0 26.7 13.0 37.6 1926 15.9 24.0 20.9 31.5 46.3 51.6 60.1 61.8 55.9 40.4 26.6 17.6 37.7 1927 13.7 25.5 31.2 38.5 46.7 53.0 59.3 53.7 55.8 43.5 32.5 16.0 39.1 1928 15.3 20.8 26.4 33.0 45.5 52.3 60.7 59.8 45.4 42.1 31.6 21.9 37.9 1929 4.0 8.5 31.3 40.0 43.8 52.1 59.7 56.0 49.8 38.7 24.5 18.1 35.6 1930 7.0 25.4 24.4 36.6 47.6 54.8 58.4 58.7 51.3 38.4 28.7 19.0 37.5 1931 20.7 24.2 27.4 1 35.3 43.0 57.5 63.5 59.6 58.5 46.4 38.3 29.3 42.0 1932 25.4 23.7 20.3 36.5 47.9 58.9 61.0 59.5 50.1 40.9 25.2 16.9 1 38.9 1933 26.1 13.2 28.2 36.9 51.1 61.1 61.5 57.5 55.7 37.2 27.3 20.6 39.7 1934 21.8 11.5 22.7 35.5 48.5 59.6 63.4 59.2 52.1 41.8 34.9 15.8 38.9 1935 14.1 21.6 31.6 36.7 43.1 53.4 64.1 61.4 50.3 40.3 30.1 16.0 38.6 1936 8.3 2.1 28.6 32.9 50.5 52.1 62.5 61.7 55.0 39.4 25.6 22.1 36.7 1937 15.0 15.4 24.4 36.8 46.8 55.4 59.9 62.5 49.2 38.7 24.4 17.5 37.2 1938 16.1 26.5 33.2 38.1 47.0 55.1 60.7 61.9 53.4 42.3 31.4 20.3 40.5 1939 23.5 16.3 27.8 35.8 51.9 59.6 61.4 60.3 55.0 41.9 30.3 27.1 40.9 1940 7.6 23.0 25.8 36.9 46.0 57.8 61.1 62.2 50.3 43.8 27.1 24.8 38.9 1941 20.1 16.2 24.3 42.2 50.1 59.1 61.7 59.9 55.3 44.4 31.9 27.7 41.1 1942 15.0 18.0 30.5 40.8 47.5 59.0 63.1 60.0 51.2 40.8 29.8 13.4 39.1 1943 13.2 16.8 20.5 35.0 47.1 62.7 62.2 63.1 48.4 39.4 25.2 17.4 37.6 1944 18.7 18.2 23.8 35.0 53.6 60.7 58.7 60.7 53.9 38.8 34.3 12.0 39.0 1945 10.0 19.1 36.7 38.6 42.2 53.6 57.3 59.2 52.6 37.1 29.5 11.2 37.3 1946 17.1 18.1 35.6 38.5 45.1 55.2 60.6 55.8 50.4 42.2 31.2 21.0 39.2 1947 17.9 11.1 22.4 36.6 43.7 55.1 58.4 66.6 53.5 49.0 25.0 21.2 38.4 1948 7.6 14.9 26.4 40.9 42.5 54.9 61.3 59.3 54.4 37.4 33.3 20.1 37.8 1949 17.9 17.5 26.8 34.4 47.3 60.6 64.9 59.8 45.1 46.3 30.5 21.0 39.4 1950 19.3 17.0 24.3 32.5 48.1 56.4 57.4 55.9 51.4 44.8 23.3 7.6 36.5 1951 12.7 16.6 25.1 35.7 48.3 54.0 59.0 57.5 47.7 41.7 20.8 13.5 36.1 1952 13.2 21.4 23.5 36.6 45.0 60.3 62.3 58.3 48.1 30.0 27.7 22.3 37.4 1953 18.6 20.0 26.7 34.4 46.3 58.4 60.1 57.5 48.0 41.0 29.2 19.0 38.3 1954 15.4 25.5 22.0 39.0 41.5 60.2 60.5 58.5 51.8 40.5 29.1 21.0 38.8 1955 13.3 16.5 24.3 42.1 49.0 54.7 67.1 63.8 52.9 41.9 24.2 15.9 38.8 1956 19.0 19.6 25.8 34.1 47.6 59.0 59.9 60.9 49.2 45.2 28.5 23.5 39.4 1957 6.3 24.1 27.5 39.7 46.5 58.8 63.9 60.0 50.8 39.1 29.7 23.4 39.2 1958 14.8 7.6 27.8 38.2 45.8 52.3 61.3 61.0 52.6 42.0 31.5 10.6 37.1 1959 6.9 15.1 26.7 37.0 53.5 58.7 59.9 66.5 55.1 41.0 22.5 26.2 39.1 1960 18.0 16.6 13.8 40.1 47.1 56.3 59.7 61.9 57.6 40.5 31.0 15.2 2 38.2 7

AVERAGE MINIMUM TEMPERATURE ( F) AURORA, IL YEAR JAN FEB MAR APR MAY JUN JUL AUG SEP OCT NOV DEC ANN 1961 11.9 23.5 30.4 33.5 43.6 55.1 61.4 60.8 55.0 42.8 29.7 14.2 38.5 1962 5.1 15.9 24.6 36.7 54.3 57.0 60.0 60.0 49.0 44.8 30.0 13.7 37.6 1963 2.4 5.5 30.4 39.0 46.5 58.0 61.8 57.8 52.1 49.0 34.3 5.3 36.9 1964 18.8 17.8 25.9 40.3 52.4 59.2 63.4 57.4 52.5 35.2 31.6 17.1 39.3 1965 13.5 14.8 20.2 37.8 51.3 56.5 60.5 59.5 53.7 40.9 30.1 26.5 38.8 1966 5.7 16.6 28.1 35.6 41.5 56.2 62.4 57.1 50.2 37.4 31.3 19.8 36.8 1967 17.4 9.1 28.4 39.7 43.3 60.8 58.6 55.3 50.5 41.2 28.0 21.0 37.8 1968 14.4 12.8 29.0 39.0 45.9 58.3 62.1 62.4 54.0 42.6 32.2 20.4 39.4 1969 12.1 20.8 22.5 38.7 48.2 54.2 63.5 61.9 54.2 40.8 28.5 18.5 38.7 1970 5.8 15.3 25.9 41.0 51.6 59.7 63.9 62.3 55.0 45.3 31.1 20.1 39.8 1971 9.0 18.6 26.6 35.6 44.9 61.3 58.2 55.5 54.5 46.3 27.4 22.9 38.4 1972 10.0 12.6 2 24.8 35.6 50.0 55.7 61.2 61.2 54.1 39.7 30.7 14.7 37.5 1973 18.3 19.3 34.4 40.2 46.3 59.9 63.6 63.8 2 56.6 47.7 33.0 20.1 41.9 1974 16.7 19.1 30.5 40.6 48.6 55.7 63.6 61.1 49.2 41.7 31.8 24.2 40.2 1975 16.8 2 16.2 22.4 32.7 51.6 59.8 2 62.4 63.5 48.7 40.1 35.5 20.0 39.1 1976 5.9 20.8 28.1 40.4 44.3 58.4 62.2 57.0 48.3 35.3 20.3 5.6 35.6 1977-1.8 12.9 31.8 41.1 54.1 54.5 63.9 59.6 54.4 39.9 31.7 15.7 38.2 1978 5.1 4.6 23.2 37.2 48.4 57.3 61.9 61.0 56.2 39.4 30.9 15.0 36.7 1979 0.0 4.4 26.0 36.4 47.2 57.1 60.4 60.6 51.7 40.9 29.2 23.0 36.4 1980 14.8 11.9 24.5 37.5 48.4 55.9 63.9 63.4 51.1 1 37.2 30.8 17.3 1 38.1 1981 12.9 16.2 27.7 40.6 44.0 58.9 61.2 60.7 51.3 38.8 30.9 16.5 38.3 1982 0.6 10.6 24.7 32.7 53.3 51.0 62.4 57.7 51.7 42.0 30.7 27.6 37.1 1983 20.5 23.3 29.0 35.3 44.5 58.4 64.6 63.1 50.8 41.6 32.7 6.5 39.2 1984 6.1 23.9 22.8 38.7 45.5 60.9 59.5 60.9 51.1 45.3 27.8 23.0 38.8 1985 5.6 11.1 30.6 42.8 50.0 54.7 61.3 58.0 53.7 41.9 30.0 6.9 37.2 1986 12.1 15.3 28.6 38.8 49.1 56.2 64.7 55.3 1 54.1 1 45.0 2 28.4 3 20.9 1 51.7 1987 15.4 22.0 32.5 40.2 51.9 60.6 66.2 2 62.4 53.4 36.1 35.6 25.5 59.9 1988 9.8 12.6 27.3 37.3 48.0 57.0 62.9 64.6 53.3 34.0 31.2 16.4 37.9 1989 22.1 7.4 25.0 34.8 44.2 56.2 61.3 60.0 47.3 37.8 24.6 6.6 35.6 1990 23.5 21.4 32.4 31.8 1 46.2 58.1 61.0 60.8 52.9 36.5 31.4 16.7 59.3 1991 9.8 19.4 28.0 40.7 53.0 61.1 64.5 63.3 53.6 42.5 25.8 22.6 40.4 1992 21.0 27.5 27.3 35.6 45.3 52.1 60.6 56.7 52.5 39.5 32.7 21.0 39.3 1993 17.7 16.2 24.7 1 36.8 50.7 58.4 66.8 63.2 49.6 37.7 26.4 19.4 56.1 1994 3.9 9.5 26.2 39.2 44.5 55.2 60.1 54.7 52.0 41.2 30.9 21.9 36.6 1995 12.3 13.3 27.0 39.8 50.1 60.5 64.7 64.8 49.4 40.2 26.0 16.8 38.8 ----- 1 Elgin data substituted for Aurora 2 De Kalb data substituted for Aurora 3 Chicago-O'Hare data substituted for Aurora 8

AVERAGE MONTHLY TEMPERATURE ( F) AURORA, IL YEAR JAN FEB MAR APR MAY JUN JUL AUG SEP OCT NOV DEC ANN 1901 23.9 14.2 34.2 47.9 58.7 72.1 80.0 72.3 63.9 54.1 35.5 22.9 48.3 1902 23.3 18.1 39.6 47.4 62.1 66.1 73.3 68.1 59.6 53.3 46.0 24.6 48.5 1903 23.0 23.0 41.1 49.0 61.8 63.4 72.4 68.6 62.1 50.9 35.4 17.8 47.4 1904 15.1 16.7 35.3 42.6 59.1 67.0 70.8 66.4 63.0 51.4 40.3 24.6 46.0 1905 17.5 15.6 40.3 47.8 58.7 68.0 70.5 71.8 64.7 50.0 38.2 28.7 47.7 1906 29.2 25.6 28.7 50.8 60.0 67.8 71.2 74.0 66.7 51.3 37.9 29.3 49.4 1907 25.0 24.8 42.4 40.4 52.4 65.5 71.9 68.5 61.4 48.3 36.6 29.4 47.2 1908 25.5 24.0 39.1 49.5 59.6 67.6 72.5 69.5 67.0 52.1 39.5 27.7 49.5 1909 26.4 30.1 34.7 45.3 57.0 67.0 70.4 73.2 61.0 46.9 46.6 17.6 48.0 1910 21.6 21.6 46.7 50.4 53.8 67.5 75.0 71.2 62.2 54.3 33.3 22.5 48.4 1911 25.6 30.3 37.5 46.1 64.8 71.3 73.0 69.3 64.7 50.0 33.5 31.2 49.8 1912 9.0 19.3 26.3 48.9 60.1 65.4 72.3 68.6 64.5 51.7 40.3 31.5 46.5 1913 26.2 1 22.6 33.2 49.6 58.5 69.9 74.0 72.5 62.6 51.0 45.4 34.2 50.0 1914 30.3 16.5 34.9 50.0 61.3 68.4 74.0 71.5 63.0 55.5 40.9 20.4 48.9 1915 18.1 32.6 32.9 56.3 54.6 64.5 68.7 64.8 64.2 53.2 41.2 25.2 48.0 1916 26.2 21.9 32.7 47.8 59.4 62.5 77.7 73.8 61.1 50.7 40.0 21.8 48.0 1917 20.1 17.6 37.4 45.2 52.6 63.7 71.7 68.1 60.3 41.9 40.0 18.7 44.8 1918 8.5 24.6 41.1 44.3 63.8 67.4 69.8 73.8 56.0 53.3 40.5 33.3 48.0 1919 26.3 28.2 37.6 48.8 56.0 72.4 75.9 71.0 66.0 54.5 36.2 17.6 49.2 1920 16.1 1 24.7 38.3 42.7 56.9 68.5 70.7 70.1 66.8 58.0 37.8 29.8 48.4 1921 30.1 31.7 45.6 53.0 63.0 76.0 81.5 72.4 67.3 52.3 37.9 29.3 53.4 1922 22.6 28.0 38.8 49.0 64.3 70.5 73.3 74.1 67.5 55.2 42.4 27.5 51.1 1923 28.3 20.1 31.6 47.4 58.4 72.2 75.4 69.6 63.6 48.7 40.3 36.2 49.3 1924 17.0 26.4 33.3 47.8 53.3 65.0 68.5 69.0 57.6 56.0 39.6 20.2 46.2 1925 21.2 30.2 38.6 54.1 55.0 70.3 72.0 72.2 68.8 42.6 36.2 21.6 48.6 1926 24.9 30.2 30.0 42.6 60.1 63.9 71.5 72.3 63.5 49.8 34.9 24.9 47.4 1927 22.0 33.5 40.6 48.2 56.9 64.4 71.8 66.2 67.6 55.6 41.9 25.2 49.5 1928 24.1 29.4 36.8 44.8 59.7 64.2 72.7 72.1 59.3 53.8 39.9 30.2 48.9 1929 15.3 18.9 42.2 50.5 56.4 64.8 72.4 69.0 62.6 49.4 34.1 25.9 46.8 1930 16.7 35.7 35.5 49.8 59.4 67.2 72.7 71.6 63.8 49.2 39.7 27.1 49.0 1931 28.7 33.5 35.6 1 49.2 55.5 70.7 76.3 72.6 69.8 56.3 47.4 35.7 52.6 1932 31.7 33.2 28.8 48.0 60.8 70.9 74.3 72.4 62.7 51.4 35.1 26.7 49.7 1933 34.7 24.1 35.9 47.5 60.6 75.8 74.7 70.6 68.7 49.7 37.7 28.9 50.8 1934 29.7 21.3 32.4 49.5 65.1 73.7 76.7 71.2 62.5 54.1 43.7 23.3 50.3 1935 23.2 28.2 41.5 46.4 53.2 64.8 76.5 72.6 63.8 52.1 37.7 23.3 48.6 1936 16.6 12.2 38.9 44.8 64.1 67.0 79.5 75.8 65.9 51.0 35.7 31.3 48.6 1937 24.2 24.6 33.0 46.9 59.4 67.0 74.1 76.2 63.0 49.4 35.9 24.6 48.2 1938 23.8 33.6 43.7 49.2 59.1 66.7 73.2 74.5 64.4 56.2 42.3 28.3 51.3 1939 30.4 25.8 38.7 46.1 64.4 71.0 74.1 72.6 69.8 54.1 39.6 34.5 51.8 1940 15.4 29.0 32.8 47.2 56.1 69.2 74.7 73.0 63.7 56.1 37.1 32.0 48.9 9

AVERAGE MONTHLY TEMPERATURE ( F) AURORA, IL YEAR JAN FEB MAR APR MAY JUN JUL AUG SEP OCT NOV DEC ANN 1941 27.3 24.8 33.0 53.9 63.6 69.8 73.8 72.6 67.6 54.3 41.2 34.5 51.4 1942 23.7 24.7 39.9 53.7 59.7 69.8 74.4 71.1 61.8 52.3 40.2 21.7 49.4 1943 22.2 27.2 31.8 46.3 56.7 72.8 74.3 73.7 60.1 51.7 34.3 26.8 48.2 1944 29.8 27.3 32.0 45.4 64.5 72.1 72.9 73.5 65.5 52.3 42.1 20.6 49.8 1945 18.0 27.0 48.7 49.5 53.8 65.3 70.3 71.1 62.6 49.7 38.6 19.3 47.8 1946 25.7 27.8 46.8 51.3 56.8 67.2 73.4 68.3 64.3 56.8 41.0 30.7 50.9 1947 26.9 19.3 31.1 47.7 55.1 66.6 70.6 78.6 65.2 61.1 33.5 29.5 48.8 1948 17.7 24.9 36.1 53.0 55.3 67.0 73.0 71.7 65.9 49.8 41.8 28.5 48.7 1949 26.1 25.8 36.4 47.3 60.3 72.8 76.3 72.4 58.0 57.5 40.3 30.3 50.3 1950 29.5 25.1 32.4 42.2 60.2 67.7 70.3 68.2 62.7 57.0 32.8 17.0 47.1 1951 21.1 25.2 34.1 46.1 61.0 65.3 70.9 68.4 59.9 53.4 30.8 23.3 46.6 1952 23.9 30.3 33.0 49.7 57.2 71.9 74.2 70.0 62.5 45.4 39.7 29.4 48.9 1953 26.4 30.1 36.6 45.2 59.0 71.3 72.9 71.8 63.5 56.1 40.7 28.5 50.2 1954 24.8 35.1 32.5 51.3 54.4 72.3 73.1 69.5 65.2 51.6 39.2 28.4 49.8 1955 21.9 25.6 35.6 55.0 61.7 66.0 78.3 75.3 65.6 53.7 34.3 24.5 49.8 1956 26.9 27.6 35.7 46.9 60.0 71.7 70.7 71.9 63.6 59.1 38.9 30.7 50.3 1957 16.2 31.8 36.8 49.3 57.4 69.4 74.6 71.3 62.3 50.3 38.7 32.3 49.2 1958 22.4 16.9 35.6 49.7 60.2 63.1 71.1 72.3 64.4 55.2 41.7 19.6 47.7 1959 16.2 23.7 36.6 48.4 64.6 70.9 72.2 76.2 66.5 49.7 31.6 33.7 49.2 1960 25.4 23.7 23.4 51.6 57.7 66.9 71.4 72.6 67.9 52.9 40.8 24.2 1 48.2 1961 21.2 32.4 39.3 43.5 55.8 68.1 71.8 71.8 66.4 53.5 38.9 23.3 48.8 1962 14.6 24.2 32.6 48.6 65.5 69.7 69.9 72.3 61.8 55.7 40.0 22.9 48.2 1963 11.1 16.5 40.2 51.4 58.1 71.0 73.0 69.4 64.4 62.2 43.9 15.0 48.0 1964 27.9 27.2 35.6 50.6 64.5 71.3 74.0 69.1 64.2 49.1 42.1 24.9 50.1 1965 22.4 24.3 27.7 47.6 63.8 68.8 72.5 69.2 63.1 52.0 40.1 34.0 48.8 1966 15.2 25.5 38.0 45.3 53.4 68.8 75.1 68.9 62.0 50.1 40.5 26.2 47.4 1967 26.1 18.6 36.9 49.8 54.6 71.3 69.9 67.0 62.6 51.0 35.5 28.7 47.7 1968 22.1 22.7 41.0 50.8 56.7 69.9 72.8 73.1 64.9 53.6 39.2 27.3 49.5 1969 19.7 28.0 33.3 50.3 59.6 64.9 73.3 73.3 64.7 51.2 36.9 25.7 48.4 1970 13.6 24.4 33.9 50.8 62.7 70.4 75.2 73.1 65.9 54.9 38.6 28.7 49.4 1971 17.6 26.5 34.4 48.2 58.1 74.3 70.5 69.6 67.3 59.1 38.8 31.7 49.7 1972 19.3 22.6 1 34.0 46.1 62.2 67.1 72.0 71.3 64.4 49.9 36.8 23.1 47.4 1973 27.2 27.3 43.7 49.3 56.6 71.3 75.0 75.1 1 66.3 58.2 41.6 27.6 51.6 1974 23.8 27.5 38.5 51.8 58.1 66.5 75.2 71.3 61.6 54.0 41.0 30.1 50.0 1975 26.7 1 25.2 32.9 44.7 65.1 71.2 1 73.3 73.7 60.0 53.8 45.3 27.8 50.0 1976 16.1 31.8 38.6 51.6 55.8 70.4 74.2 69.3 61.5 46.4 30.7 16.7 46.9 1977 7.9 23.5 41.8 54.1 67.1 67.2 75.1 69.6 63.9 50.3 39.4 23.1 48.6 1978 14.2 15.3 31.8 48.7 58.7 68.0 70.7 71.3 68.6 50.5 39.6 23.5 46.8 1979 9.9 14.0 35.0 45.4 59.7 69.0 71.6 70.3 63.6 1 50.2 1 37.8 1 30.1 1 46.4 1980 21. 7 1 19.6 1 31.4 1 45.9 1 61.1 67.4 75.2 73.5 62.2 1 48.2 39.6 24.7 1 47.5 10

AVERAGE MONTHLY TEMPERATURE ( F) AURORA, IL YEAR JAN FEB MAR APR MAY JUN JUL AUG SEP OCT NOV DEC ANN 1981 22.3 26.7 38.6 51.9 55.9 69.8 71.1 70.6 62.0 49.7 40.2 24.7 48.6 1982 11.5 20.6 34.0 44.2 65.2 63.9 73.3 68.8 62.7 54.2 39.0 35.1 47.7 1983 26.8 31.0 37.9 44.6 55.2 70.5 77.3 75.4 63.7 52.5 41.4 14.1 49.2 1984 16.3 33.2 29.8 47.7 57.0 71.9 71.4 73.9 62.6 55.8 1 38.9 1 31.249.1 1 1985 15.0 20.2 39.9 53.7 62.3 66.4 72.6 68.9 64.8 52.6 37.2 16.9 47.6 1986 22.1 23.1 39.9 52.1 60.5 68.0 75.2 66.7 1 54.1 1 53.7 1 36.0 1 28.2 1 48.3 1987 23.6 32.3 41.7 51.6 64.4 72.3 75.5 1 71.7 64.4 47.2 43.5 31.7 51.7 1988 19.1 22.2 37.6 48.8 62.7 71.8 76.8 76.1 66.1 45.8 40.2 26.9 49.5 1989 31.2 18.0 35.6 47.0 57.5 68.1 73.2 70.7 60.3 51.6 35.7 15.9 47.1 1990 32.6 30.6 41.1 45.1 1 56.6 69.9 71.4 71.1 64.9 50.1 42.5 26.5 50.2 1991 19.6 29.1 39.0 52.3 65.8 73.8 76.6 74.8 65.1 53.0 34.7 30.4 51.2 1992 28.1 33.8 37.6 46.3 58.6 66.1 70.2 67.4 62.8 50.7 37.9 27.6 48.9 1993 25.7 24.1 32.1 1 46.3 61.9 68.3 75.2 72.6 58.9 49.5 36.2 27.1 48.2 1994 13.5 20.3 37.2 50.9 58.6 69.3 71.5 66.5 64.2 52.7 41.1 31.3 48.1 1995 21.2 23.7 38.7 48.4 59.6 71.9 76.0 76.5 61.5 52.3 33.5 25.1 49.0 ----- 1 Elgin data substituted for Aurora 2 Dixon data substituted for Aurora 3 Chicago-O'Hare data substituted for Aurora HEATING DEGREE DAYS (Base:65F) AURORA, IL Yr Jul Aug Sep Oct Nov Dec Jan Feb Mar Apr May Jun Season 1900-01 1266 1417 948 497 217 47. 1901-02 0 4 113 340 876 1303 1282 1307 781 525 160 62 6753 1902-03 8 21 175 360 567 1247 1295 1169 736 475 161 94 6308 1903-04 3 20 133 437 882 1459 1544 1396 913 666 207 32 7692 1904-05 10 34 108 427 734 1243 1464 1377 757 512 210 38 6914 1905-06 12 0 61 459 796 1118 1103 1097 1119 419 214 43 6441 1906-07 4 10 48 420 807 1101 1234 1119 698 731 389 73 6634 1907-08 9 29 162 512 848 1096 1215 1182 798 461 219 61 6592 1908-09 3 30 76 405 758 1151 1189 971 935 582 256 49 6405 1909-10 21 13 174 556 549 1459 1340 1209 561 439 343 91 6755 1910-11 0 14 118 344 943 1311 1213 966 846 564 135 6 6460 1911-12 16 30 68 460 935 1041 1732 1320 1192 466 188 60 7508 1912-13 9 35 151 392.736 966 1166 1 1180 979 461 221 65 6361 1913-14 5 2 160 446 583 945 1068 1355 928 422 189 50 6153 1914-15 0 7 131 303 717 1375 1449 903 988 303 317 81 6574 1915-16 18 81 102 362 708 1224 1197 1246 994 509 212 105 6758 1916-17 0 14 191 444 745 1335 1386 1323 844 586 398 85 7351 1917-18 12 18 161 709 743 1430 1747 1125 733 614 127 34 7453 1918-19 25 2 266 358 728 839 1193 1025 846 479 296 11 6068 11

HEATING DEGREE DAYS (Base:65F) AURORA, IL Yr Jul Aug Sep Oct Nov Dec Jan Feb Mar Apr May Jun Season 1919-20 0 11 68 353 858 1465 1602 1 1163 821 663 254 59 7317 1920-21 11 33 55 242 810 1085 1073 925 598 357 184 21 5394 1921-22 0 17 55 389 806 1100 1309 1030 805 473 62 15 6061 1922-23 2 9 90 334 671 1154 1133 1252 1029 521 214 32 6441 1923-24 0 21 111 501 736 888 1482 1116 975 507 358 82 6777 1924-25 35 26 238 276 757 1383 1347 969 814 343 321 28 6537 1925-26 5 4 56 689 857 1340 1235 971 1080 668 184 81 7170 1926-27 12 0 76 472 896 1195 1324 876 748 503 268 107 6477 1927-28 6 39 108 295 685 1226 1261 1026 866 599 180 90 6381 1928-29 3 7 220 360 743 1075 1537 1286 700 456 322 88 6797 1929-30 12 20 142 474 921 1204 1491 813 910 461 222 57 6727 1930-31 24 9 104 496 750 1168 982 842 9941 465 310 52 6196 1931-32 0 5 53 286 520 901 1025 920 1118 503 163 8 5502 1932-33 3 1 113 412 889 1252 1 936 1141 863 520 169 18 6317 1933-34 0 6 51 466 815 1112 1090 1219 1002 460 104 9 6334 1934-35 1 41 133 330 633 1287 1291 1025 722 555 359 75 6452 1935-36 0 34 114 397 813 1284 1498 1525 803 604 117 46 7235 1936-37 0 1 100 426 875 1040 1258 1126 984 538 211 53 6612 1937-38 6 0 157 493 865 1246 1272 872 658 471 216 31 6287 1938-39 0 1 95 279 677 1130 1067 1091 812 569 134 33 5888 1939-40 1 3 60 365 757 938 1534 1038 992 524 289 17 6518 1940-41 12 22 130 278 828 1016 1161 1120 985 342 136 30 6060 1941-42 3 9 70 346 710 939 1275 1125 773 363 221 43 5877 1942-43 5 15 206 388 738 1337 1321 1050 1020 552 285 33 6950 1943-44 2 5 195 406 916 1180 1087 1088 1015 582 128 33 6637 1944-45 3 11 77 397 682 1370 1452 1062 486 469 360 90 6459 1945-46 16 14 156 454 787 1365 1213 1035 556 410 254 92 6352 1946-47 0 30 97 257 711 1056 1176 1271 1046 514 305 68 6531 1947-48 16 1 154 144 939 1094 1461 1160 888 377 297 42 6573 1948-49 2 4 66 466 691 1122 1200 1092 877 526 193 14 6253 1949-50 1 2 222 257 730 1065 1093 1111 1003 676 176 54 6390 1950-51 6 22 103 269 960 1483 1354 1108 950 573 168 56 7052 1951-52 3 17 177 1 379 1021 1307 1268 999 986 455 255 22 6889 1952-53 2 13 129 606 753 1099 1190 972 877 589 219 13 6462 1953-54 4 5 128 286 724 1125 1240 832 1003 410 336 45 6138 1954-55 1 12 85 434 767 1136 1331 1096 906 296 153 62 6279 1955-56 0 3 73 352 916 1249 1174 1078 903 546 213 41 6548 1956-57 1 14 101 187 775 1056 1505 921 868 477 246 27 6178 1957-58 0 4 125 449 781 1008 1310 1344 908 455 180 91 6655 1958-59 0 11 97 304 694 1402 1506 1151 875 491 128 16 6675 1959-60 2 0 80 468 992 965 1221 1190 1282 410 233 42 6885 12

HEATING DEGREE DAYS (Base:65F) AURORA, IL Yr Jul Aug Sep Oct Nov Dec Jan Feb Mar Apr May Jun Season 1960-61 5 2 60 373 721 1314 1 1350 905 791 637 303 45 6506 1961-62 10 7 116 358 776 1287 1560 1134 993 502 117 27 6887 1962-63 8 2 162 315 745 1298 1667 1353 759 403 236 26 6974 1963-64 4 15 91 124 628 1550 1143 1090 906 429 101 30 6111 1964-65 5 34 125 486 679 1237 1314 1132 1149 514 110 30 6815 1965-66 2 37 127 407 741 955 1539 1099 826 584 364 51 6732 1966-67 0 12 137 461 725 1197 1201 1292 865 460 335 8 6693 1967-68 21 42 128 447 878 1119 1325 1220 737 419 257 23 6616 1968-69 9 14 65 387 769 1163 1400 1029 976 433 230 104 6579 1969-70 7 0 87 444 837 1213 1589 1131 960 443 155 29 6895 1970-71 1 0 81 312 787 1117 1467 1071 950 495 237 8 6526 1971-72 16 6 94 211 781 1022 1466 1249 1 943 566 169 56 6579 1972-73 13 16 88 460 839 1292 1167 1049 656 466 260 1 6307 1973-74 0 5 1 69 232 696 1153 1271 1043 814 394 234 48 5959 1974-75 0 3 142 357 714 1072 1231 1 1107 985 602 84 31 1 6328 1975-76 9 0 176 352 609 1128 1500 961 785 447 287 16 6270 1976-77 0 17 138 579 1023 1491 1763 1160 715 346 89 62 7383 1977-78 0 16 83 454 755 1293 1573 1389 1026 482 256 39 7366 1978-79 3 8 62 446 753 1283 1702 1424 924 583 216 28 7432 1979-80 10 23 88 1 434 1 786 1 1103 2 1374 1 1363 1 1096 1 591 1 162 51 7081 1980-81 0 3 131 1 518 756 1268 1 1317 1066 811 388 291 5 6554 1981-82 13 8 123 472 734 1243 1656 1240 954 618 73 73 7207 1982-83 4 27 138 347 775 924 1178 948 833 611 298 26 6109 1983-84 4 0 132 388 702 1573 1505 917 1080 518 254 11 7084 1984-85 7 0 158 351 1 823 1 1153 1 1546 1248 769 376 133 61 6625 1985-86 0 8 140 377 828 1484 1327 1165 775 405 166 45 6720 1986-87 3 42 1 99 1 439 1 923 1 1145 1 1276 910 716 404 147 13 6117 1987-88 4 1 20 78 548 641 1029 1421 1235 842 480 130 28 6456 1988-89 0 9 53 586 735 1176 1039 1306 906 537 269 32 6648 1989-90 0 11 167 411 872 1516 999 958 738 538 1 260 30 6500 1990-91 11 8 125 464 672 1189 1401 999 800 384 136 7 6196 1991-92 0 0 152 367 902 1070 1136 901 846 554 236 55 6219 1992-93 14 28 133 441 808 1152 1211 1139 1020 1 553 145 49 6693 1993-94 0 6 197 476 858 1170 1593 1245 859 441 229 48 7122 1994-95 4 41 92 374 702 1037 1349 1151 811 505 177 30 6273 1995-96 1 0 164 388 944 1229 1 Marengo data substituted for Aurora 2 Elgin data substituted for Aurora 13

COOLING DEGREE DAYS AURORA, IL YEAR JAN FEB MAR APR MAY JUN JUL AUG SEP OCT NOV DEC ANN 1901 0 0 0 4 31 264 472 235 84 10 0 0 1100 1902 0 0 0 3 77 100 272 124 22 3 2 0 603 1903 0 0 2 3 65 54 239 138 54 10 0 0 565 1904 0 0 0 0 27 100 199 83 55 11 0 0 475 1905 0 0 0 2 21 139 191 216 61 1 0 0 631 1906 0 0 0 0 65 134 201 297 106 2 0 0 805 1907 0 0 5 0 10 95 229 146 61 3 0 0 549 1908 0 0 0 0 56 143 243 178 142 12 0 0 774 1909 0 0 0 0 15 117 196 275 59 0 1 0 663 1910 0 0 1 8 4 171 317 211 39 20 0 0 771 1911 0 0 0 0 136 201 273 170 65 0 0 0 845 1912 0 0 0 0 44 81 244 155 144 2 0 0 670 1913 0 0 0 3 29 216 292 241 91 16 0 0 888 1914 0 0 0 16 81 161 286 216 76 18 0 0 858 1915 0 0 0 45 2 71 138 81 86 0 0 0 423 1916 0 0 0 0 46 38 401 295 80 8 0 0 868 1917 0 0 0 0 19 52 226 122 25 0 0 0 444 1918 0 0 0 0 94 112 178 283 2 0 0 0 669 1919 0 0 0 1 24 241 346 202 104 35 0 0 953 1920 0 5 0 0 0 12 171 191 197 115 33 0 0 719 1921 0 0 5 7 131 360 520 251 130 2 0 0 1406 1922 0 0 0 0 46 186 270 296 172 36 0 0 1006 1923 0 0 0 0 15 257 326 172 75 0 0 0 845 1924 0 0 0 0 0 88 148 159 20 2 3 0 420 1925 0 0 0 22 20 191 228 233 176 0 0 0 870 1926 0 0 0 2 41 55 220 233 80 9 0 0 628 1927 0 0 0 4 24 95 221 82 192 12 0 0 630 1928 0 0 0 1 21 72 250 236 57 23 0 0 660 1929 0 0 0 29 63 89 247 149 79 0 0 0 656 1930 0 0 0 15 56 130 247 223 74 13 0 0 758 1931 0 0 0 5 0 0 22 176 341 251 201 24 0 1015 1932 0 0 0 0 40 192 298 235 51 1 0 0 817 1933 0 0 0 2 41 349 305 186 169 0 2 0 1054 1934 0 0 0 0 115 274 373 241 62 0 0 0 1065 1935 0 0 0 2 0 74 362 278 85 6 0 0 807 1936 0 0 0 5 95 110 457 341 133 0 0 0 1141 1937 0 0 0 0 47 119 292 353 102 17 0 0 930 1938 0 0 3 3 40 89 262 300 83 14 2 0 796 1939 0 0 3 8 122 220 290 246 212 36 0 0 1137 1940 0 0 0 0 22 149 318 277 94 7 0 0 867 14

COOLING DEGREE DAYS YEAR JAN FEB MAR APR MAY AURORA, IL JUN JUL AUG SEP OCT NOV DEC ANN 1941 0 0 0 15 100 181 281 253 156 17 0 0 1003 1942 0 0 0 29 65 197 302 213 118 3 0 0 927 1943 0 0 0 0 32 273 295 279 54 0 0 0 933 1944 0 0 0 0 117 254 256 284 98 11 1 0 1021 1945 0 0 0 5 13 105 190 208 87 0 0 0 608 1946 0 0 0 5 7 164 268 140 83 12 0 0 679 1947 0 0 0 0 4 123 186 431 168 30 0 0 942 1948 0 0 0 21 4 112 257 219 102 1 0 0 716 1949 0 0 0 2 55 257 355 236 18 32 0 0 955 1950 0 0 0 0 34 138 174 127 40 23 5 0 541 1951 0 0 0 12 51 77 187 127 48 5 27 0 0 529 1952 0 0 0 2 20 234 294 173 59 5 0 0 787 1953 0 0 0 0 40 208 256 221 89 19 0 0 833 1954 0 0 0 3 15 273 260 157 98 23 0 0 829 1955 0 0 0 1 60 98 418 329 100 10 0 0 1016 1956 0 0 0 9 64 251 188 236 66 11 0 0 825 1957 0 0 0 12 19 166 304 210 53 0 0 0 764 1958 0 0 0 0 39 40 195 245 83 9 0 0 611 1959 0 0 0 0 123 198 230 357 134 0 0 0 1042 1960 0 0 0 15 11 104 208 245 155 4 0 0 742 1961 0 0 0 0 26 143 227 224 162 8 0 0 790 1962 0 0 0 15 139 174 167 236 71 31 0 0 833 1963 0 0 0 3 33 212 259 158 77 46 0 0 788 1964 0 0 0 3 93 226 290 169 107 0 0 0 888 1965 0 0 0 0 79 152 241 172 74 11 0 0 729 1966 0 0 0 0 13 172 320 141 58 2 0 0 706 1967 0 0 0 3 19 204 188 109 66 19 0 0 608 1968 0 0 0 0 9 177 260 272 72 39 0 0 829 1969 0 0 0 0 65 108 270 263 85 25 0 0 816 1970 0 0 0 25 88 195 326 258 112 5 0 0 1009 1971 0 0 0 0 30 295 195 160 171 35 0 0 886 1972 0 0 0 0 87 128 238 220 77 0 0 0 750 1973 0 0 0 0 4 196 317 313 1 115 30 0 0 975 1974 0 0 0 5 29 101 322 205 39 7 0 0 708 1975 0 0 0 0 97 186 5 273 277 32 14 0 0 879 1976 0 0 0 27 7 185 288 155 40 10 0 0 712 1977 0 0 0 25 162 133 318 164 57 0 0 0 859 1978 0 0 0 0 65 133 186 208 175 0 0 0 767 1979 0 0 0 0 55 155 220 194 96 5 0 5 0 5 0 5 720 1980 0 5 0 5 0 5 0 5 48 129 328 272 116 5 3 0 0 5 896 15

COOLING DEGREE DAYS AURORA, IL YEAR JAN FEB MAR APR MAY JUN JUL AUG SEP OCT NOV DEC ANN 1981 0 0 0 3 14 153 208 191 42 0 0 0 611 1982 0 0 0 0 82 46 265 152 72 20 0 0 637 1983 0 0 0 0 2 196 392 330 98 9 0 0 1027 1984 0 0 0 5 12 226 212 280 93 0 5 0 5 0 5 828 1985 0 0 0 45 55 109 242 137 140 0 0 0 728 1986 0 0 2 22 33 142 328 100 5 167 5 0 5 0 5 0 5 793 1987 0 0 0 7 135 237 326 5 227 64 0 0 0 996 1988 0 0 0 1 64 237 372 358 91 0 0 0 1123 1989 0 0 0 2 44 132 261 196 31 3 0 0 669 1990 0 0 3 0 5 6 183 216 205 127 10 1 0 751 1991 0 0 0 8 170 278 369 312 160 4 0 0 1301 1992 0 0 0 0 40 94 184 111 74 2 0 0 505 1993 0 0 0 5 0 60 154 320 247 18 3 0 0 802 1994 0 0 0 23 37 181 213 94 77 1 0 0 626 1995 0 0 0 0 16 241 349 366 64 1 0 0 1037 ----- 5 values based on mean monthly temperature, as opposed to daily accumulated degree days GROWING DEGREE DAYS AURORA, IL YEAR JAN FEB MAR APR MAY JUN JUL AUG SEP OCT NOV DEC ANN 1901 0 0 2 0 280 667 937 696 428 185 7 0 3202 1902 0 0 14 69 391 488 729 568 298 142 69 0 2768 1903 0 0 26 87 382 413 701 583 378 126 24 0 2720 1904 0 0 1 32 298 518 654 514 397 132 8 0 2554 1905 0 0 46 79 280 551 644 681 450 164 3 0 2898 1906 0 0 0 108 342 541 662 752 508 141 13 0 3067 1907 0 0 79 11 158 472 685 582 357 85 0 0 2429 1908 0 0 5 102 347 532 705 613 529 172 11 0 3016 1909 8 0 0 44 263 518 640 727 338 96 65 0 2699 1910 0 0 110 142 163 533 782 662 371 209 3 0 2975 1911 0 0 10 69 489 645 722 605 447 109 17 3 3116 1912 0 0 0 0 337 471 700 585 460 53 19 0 2211 1913 0 0 6 93 282 602 752 704 396 189 72 6 3102 1914 0 0 5 0 368 561 751 674 395 237 29 2 3022 1915 0 0 0 262 169 442 585 465 434 147 42 0 2546 1916 0 0 8 74 316 383 866 746 356 108 31 4 2892 1917 0 0 14 52 156 417 679 569 320 27 5 0 2239 1918 0 0 23 38 440 528 618 746 200 144 14 0 2751 1919 0 0 14 91 201 680 811 656 486 212 3 0 3154 16

GROWING DEGREE DAYS AURORA,IL YEAR JAN FEB MAR APR MAY JUN JUL AUG SEP OCT NOV DEC ANN 1920 0 5 0 30 34 249 562 645 629 504 298 4 3 2958 1921 0 0 60 90 441 789 985 699 525 118 7 0 3714 1922 0 2 6 85 449 621 733 752 532 211 28 0 3419 1923 0 0 0 81 275 675 791 616 420 88 0 0 2946 1924 0 0 0 63 134 456 578 598 243 221 39 0 2332 1925 0 1 12 173 200 613 688 694 570 56 0 0 3007 1926 0 0 2 56 336 424 673 698 405 123 2 0 2719 1927 0 0 13 89 230 438 680 508 538 217 35 0 2748 1928 0 0 30 57 312 432 712 694 316 219 15 0 2787 1929 0 0 25 134 253 452 700 594 395 75 0 0 2628 1930 0 17 5 119 313 523 704 679 428 161 37 0 2986 1931 0 0 0 5 0 120 209 815 711 598 232 90 0 2775 1932 0 1 0 65 342 634 760 699 388 140 2 0 3031 1933 0 0 0 61 353 781 770 645 568 107 27 0 3312 1934 0 0 0 85 477 715 837 665 379 187 41 0 3386 1935 0 0 23 70 164 449 827 709 424 141 4 0 2811 1936 0 0 15 92 446 514 922 805 483 142 16 2 3437 1937 0 0 0 70 311 516 751 818 403 124 14 0 3007 1938 0 1 59 142 306 508 727 764 443 224 66 0 3240 1939 0 0 41 89 459 637 754 708 605 217 2 0 3512 1940 0 0 12 56 240 582 771 720 416 207 12 0 3016 1941 0 0 0 183 431 601 743 709 536 191 23 2 3419 1942 0 0 17 208 323 604 762 663 417 182 21 0 3197 1943 0 0 25 49 230 690 758 739 311 141 0 0 2943 1944 5 0 0 35 473 671 718 738 471 140 57 0 3308 1945 0 0 0 97 188 474 639 659 389 0 34 0 2480 1946 0 0 58 142 230 525 733 575 438 244 9 15 2969 1947 0 0 0 62 203 505 639 895 484 354 9 0 3151 1948 0 0 28 169 186 520 720 680 486 73 30 0 2892 1949 0 0 13 77 330 693 819 699 256 271 51 0 3209 1950 0 0 1 23 331 534 633 570 392 247 21 0 2752 1951 0 0 10 72 358 471 649 575 105 183 7 2 2432 1952 0 0 5 140 243 662 757 625 380 55 25 0 2892 1953 0 0 10 51 293 645 717 681 414 228 35 0 3074 1954 0 3 4 150 204 678 724 610 463 163 9 0 3008 1955 0 0 3 179 379 486 883 791 477 173 10 0 3381 1956 0 0 0 75 328 660 652 687 420 298 61 4 3185 1957 0 3 10 164 256 589 769 671 379 98 3 0 2942 1958 0 0 0 83 334 399 660 699 437 198 48 0 2858 1959 0 0 10 76 463 632 693 822 504 110 3 2 3315 1960 0 0 5 163 289 512 668 708 545 162 24 0 5 3076 17

GROWING DEGREE DAYS YEAR JAN FEB MAR APR MAY AURORA,IL JUN JUL AUG SEP OCT NOV DEC ANN 1961 0 0 11 32 211 548 682 682 503 176 18 0 2863 1962 0 0 7 123 494 597 624 699 361 266 0 0 3171 1963 0 0 45 132 276 636 720 608 436 399 31 0 3283 1964 0 0 0 120 457 646 750 600 433 87 79 0 3172 1965 0 0 0 50 442 572 704 600 401 139 33 1 2942 1966 0 0 11 39 196 571 785 594 371 95' 34 0 2696 1967 2 0 37 121 196 646 632 532 397 151 2 0 2716 1968 0 0 45 112 225 604 716 723 457 180 8 2 3072 1969 0 0 6 96 322 457 728 728 448 172 0 0 2957 1970 0 0 0 155 411 616 790 723 481 188 1 5 3370 1971 0 0 11 95 275 737 644 619 527 301 26 0 3235 1972 0 0 3 64 396 522 690 669 444 109 1 0 2898 1973 0 0 25 110 222 645 782 773 496 283 17 4 3362 1974 0 0 12 149 287 503 787 667 354 166 33 0 2958 1975 0 0 3 71 478 5 636 729 742 306 170 94 1 3230 1976 0 3 25 143 218 619 753 603 352 96 0 0 2812 1977 0 0 39 209 542 521 783 613 424 61 60 0 3252 1978 0 0 8 62 310 544 648 665 563 91 35 0 2926 1979 0 0 12 59 309 577 675 636 408 5 6 5 0 5 0 5 2682 1980 0 5 0 5 0 5 0 5 355 528 793 734 366 88 10 0 5 2874 1981 0 0 28 126 222 598 660 648 369 92 32 0 2775 1982 0 0 5 50 474 423 726 590 385 198 25 19 2895 1983 0 0 42 47 185 620 853 795 429 130 27 0 3128 1984 0 0 0 55 229 665 670 745 396 180 0 0 2940 1985 0 0 13 226 387 498 707 594 451 118 7 0 3001 1986 0 0 64 150 336 547 790 5 518 5 123 5 115 5 0 5 0 5 2643 1987 0 0 28 115 456 674 791 5 672 436 55 44 0 3271 1988 0 0 11 62 399 659 837 814 488 74 9 0 3353 1989 2 0 30 76 272 550 726 650 326 165 7 0 2804 1990 0 0 64 0 5 222 603 670 662 454 123 46 0 2844 1991 0 0 30 141 506 721 834 777 468 159 15 0 3651 1992 0 0 27 49 306 489 635 548 390 119 6 0 2569 1993 0 0 0 5 63 380 555 785 706 278 101 5 0 2873 1994 0 2 5 121 281 583 674 518 435 142 22 0 2783 1995 0 0 26 58 304 661 813 831 374 153 4 0 3224 ----- values based on mean monthly temperature, as opposed to daily accumulated degree days. 18

PRECIPITATION (inches) AURORA IL YEAR JAN FEB MAR APR MAY JUN JUL AUG SEP OCT NOV DEC ANN 1901 1.39 1.73 4.11 0.39 0.71 1.81 4.79 1.06 2.34 1.27 1.21 1.40 22.21 1902 0.47 2.05 3.14 2.16 6.1813.19 7.43 2.32 7.29 2.02 2.93 1.71 50.89 1903 0.83 1.94 3.94 4.23 3.11 4.09 5.59 5.39 7.45 2.69 0.54 1.74 41.54 1904 2.12 1.47 5.02 4.21 2.51 1.96 3.81 5.62 5.05 1.53 0.06 1.69 35.05 1905 0.93 1.33 2.33 3.85 5.94 6.16 2.72 4.00 2.36 2.32 2.21 1.35 35.50 1906 3.10 2.52 2.12 1.57 3.10 1.67 2.12 3.80 8.31 2.25 2.64 2.48 35.68 1907 3.69 0.26 3.07 2.00 4.90 3.80 5.51 6.72 6.08 1.43 1.62 1.07 40.15 1908 0.81 3.86 3.58 3.10 7.19 1.43 4.50 5.35 0.95 0.67 2.02 0.97 34.43 1909 1.43 2.57 1.34 8.38 2.64 4.71 0.48 2.92 3.28 1.25 4.33 3.43 36.76 1910 2.35 0.82 0.36 3.96 6.20 0.50 1.66 4.04 4.47 1.20 1.44 1.11 28.11 1911 1.13 1.70 1.13 2.23 2.31 4.64 2.06 5.84 7.23 3.64 2.78 1.77 36.46 1912 0.49 1 0.80 1.14 2.63 5.33 1.52 4.33 2.74 2.55 4.58 1.70 0.97 27.90 1913 1.53 1 2.80 3.43 2.16 7.01 1.05 3.58 4.37 1.68 3.85 1.74 0.46 33.25 1914 2.64 0.85 1.61 0.98 5.53 6.54 1.23 3.67 2.84 2.96 0.88 2.68 32.41 1915 2.39 2.47 0.50 0.62 8.62 3.05 9.60 5.35 4.35 1.14 2.05 1.30 41.44 1916 4.80 0.85 2.45 1.88 3.74 7.19 0.42 1.16 4.15 4.42 2.36 2.53 35.95 1917 1.82 0.45 2.69 2.32 3.96 6.79 5.91 1.87 2.26 3.25 0.35 0.51 32.18 1918 2.80 2.25 0.45 3.69 4.27 1.23 3.15 2.94 2.24 3.72 2.63 2.41 31.78 1919 0.18 2.59 4.27 3.03 4.12 3.26 2.35 0.35 4.19 5.29 2.67 1.60 33.90 1920 1.17 1 0.17 6.12 4.45 2.42 4.31 0.58 3.18 1.83 1.63 0.89 2.28 29.03 1921 0.81 0.42 4.72 4.87 2.38 3.22 0.95 3.50 5.99 2.85 2.85 4.37 36.93 1922 1.42 0.44 4.44 2.10 4.47 0.48 3.55 1.52 4.12 3.18 2.72 1.10 29.54 1923 0.71 0.75 3.12 1.57 2.98 2.86 3.12 2.79 2.94 5.11 1.82 1.72 29.49 1924 1.49 1.45 2.95 1.39 3.02 6.54 2.68 6.91 2.99 0.58 0.74 1.98 32.72 1925 0.65 1.94 0.69 3.59 1.57 6.06 2.49 0.38 4.42 3.10 2.13 1.09 28.11 1926 1.38 2.33 1.49 1.40 2.26 8.76 3.42 1.70 7.54 1.89 5.40 0.76 38.33 1927 1.27 0.86 2.23 6.52 3.58 2.41 1.13 2.34 5.72 2.67 5.55 2.01 36.29 1928 0.42 1.43 1.52 2.88 1.34 4.47 4.90 4.75 1.02 4.01 3.97 2.69 33.40 1929 4.11 0.51 3.02 6.35 2.45 7.19 3.56 1.80 3.01 2.98 1.28 1.31 37.57 1930 2.33 1.70 1.60 3.12 1.80 5.60 1.28 4.08 4.54 3.07 1.88 0.32 31.32 1931 0.59 0.49 3.06 1 2.00 4.06 6.02 2.33 1.95 4.12 4.62 5.67 2.68 37.59 1932 2.79 1.65 3.10 1.15 2.57 4.76 2.91 4.44 1.05 3.78 1.15 2.82 1 32.17 1933 2.25 1.15 2.96 3.18 6.81 2.48 3.59 1.74 3.85 3.16 0.60 0.75 32.52 1934 0.82 0.39 0.74 1.29 0.56 5.44 1.55 2.15 5.31 1.90 5.63 1.15 26.93 1935 2.20 1.46 3.26 2.12 5.16 3.89 3.76 7.58 4.18 2.11 4.23 1.09 41.04 1936 1.29 1.08 0.84 2.04 2.67 0.67 0.43 5.19 10.232.47 0.93 4.14 31.98 1937 2.78 1.06 1.02 4.47 2.54 4.89 0.41 4.95 2.19 1.94 1.45 1.04 28.74 1938 2.64 1.95 3.57 1.94 4.12 6.78 4.26 3.86 5.88 1.44 1.14 1.03 38.61 1939 2.96 2.67 1.81 3.67 2.76 3.85 1.41 2.40 1.05 3.77 0.89 0.65 27.89 1940 1.65 1.26 1.72 2.78 5.60 5.10 1.08 5.89 0.34 4.14 2.06 1.65 33.27 1941 3.07 1.17 3.27 2.03 3.97 4.04 3.21 1.46 7.30 8.53 2.19 0.78 41.02 1942 0.75 2.05 1.87 1.12 3.32 2.08 2.76 6.49 4.65 1.19 5.57 3.11 34.96 19

PRECIPITATION (inches) AURORA,IL IL YEAR JAN FEB MAR APR MAY JUN JUL AUG SEP OCT NOV DEC ANN 1943 1.75 1.07 1.68 2.96 7.77 3.13 3.03 4.82 1.15 1.65 1.40 0.34 30.75 1944 0.89 1.23 4.16 3.02 3.85 3.04 1.71 2.10 2.99 0.47 0.62 1.24 25.32 1945 1.06 1.27 2.33 4.08 6.74 5.26 0.65 3.55 9.28 0.59 2.75 1.95 39.51 1946 2.22 0.79 3.30 0.81 3.46 3.52 0.82 3.32 1.47 2.29 3.10 1.62 26.72 1947 1.79 0.12 1.71 7.18 4.66 4.86 2.96 4.43 3.42 2.04 2.50 1.30 36.97 1948 0.82 1.34 6.04 1.75 4.08 4.75 3.06 2.13 2.12 0.96 3.63 2.76 33.44 1949 3.91 2.57 2.26 1.01 2.33 3.31 4.40 0.98 3.24 2.87 0.34 6.31 33.53 1950 4.06 2.79 2.42 4.87 0.7410.25 3.04 0.84 2.79 1.32 1.18 2.53 36.83 1951 1.74 2.61 1.78 2.63 5.39 3.38 4.38 3.84 5.34 2.64 2.60 2.97 39.30 1952 1.85 0.28 3.89 2.75 2.32 5.00 3.18 3.89 1.10 0.33 2.72 2.45 29.76 1953 1.55 1.70 2.92 2.60 2.67 5.30 5.00 0.99 2.10 0.46 0.77 2.73 28.79 1954 1.32 1.72 4.59 2.93 2.86 3.72 5.31 5.54 0.6914.86 1.52 1.96 47.02 1955 1.37 2.27 2.12 2.95 2.90 3.86 3.68 4.76 1.99 4.87 2.15 1.44 34.36 1956 0.88 2.58 0.67 2.75 2.98 2.33 3.41 2.90 0.85 0.39 1.43 0.92 22.09 1957 2.58 2.41 1.40 4.42 5.27 3.96 6.83 1.87 2.05 2.50 2.43 2.43 38.15 1958 1.31 0.46 0.44 2.96 2.65 7.51 4.61 3.19 2.01 1.38 1.76 1.06 29.34 1959 2.09 3.05 4.42 5.24 4.14 2.14 6.68 3.26 2.62 4.73 3.52 1.81 43.70 1960 3.85 1.76 1.89 3.86 3.32 2.95 4.08 3.54 2.32 2.40 0.93 0.60 1 31.50 1961 0.08 0.85 2.66 2.25 2.27 5.40 3.85 2.9110.97 3.63 1.18 1.59 37.64 1962 2.54 1.69 1.79 1.73 4.69 2.25 3.62 0.71 1.19 0.79 0.88 0.35 22.23 1963 0.85 1.07 2.67 5.01 2.85 3.21 7.60 0.66 2.92 0.66 1.93 0.58 30.01 1964 0.85 0.73 2.83 5.53 1.53 5.07 5.74 1.93 4.19 0.24 2.45 1.65 32.74 1965 4.56 1.72 2.12 3.87 1.53 2.64 2.98 8.31 6.88 0.78 1.29 3.28 39.96 1966 1.57 1.76 1.82 6.01 5.18 2.03 4.11 2.08 1.54 1.93 4.19 2.52 34.74 1967 2.72 1.63 2.10 4.13 1.55 4.52 1.23 1.30 2.53 4.40 2.68 2.91 31.70 1968 1.21 0.99 0.69 2.60 3.63 2.95 2.88 3.68 3.23 1.10 3.35 3.45 29.76 1969 1.93 0.09 1.23 4.20 2.24 8.70 6.29 1.53 2.14 5.95 1.43 1.80 37.53 1970 1.19 0.90 1.90 6.04 6.21 6.03 2.26 1.76 8.97 2.81 2.04 1.36 41.47 1971 1.24 1.98 1.25 0.98 1.95 3.81 2.43 3.37 2.58 0.95 2.08 4.74 27.36 1972 1.19 1.19 4.70 3.31 3.67 5.14 3.4514.49 4.64 2.77 2.66 4.29 51.50 1973 1.42 1.17 4.75 4.17 6.99 3.15 2.28 1.40 2.01 4.08 1.98 4.31 37.71 1974 2.88 1.71 1.72 4.32 7.74 6.41 3.93 3.33 1.76 1.83 3.32 2.07 41.02 1975 2.80 2.40 1.73 6.30 6.57 6.86 1 3.62 4.98 1.10 3.39 2.08 2.69 44.52 1976 0.89 1.02 5.32 3.81 3.57 3.42 2.59 1.75 2.27 2.06 0.50 0.61 27.81 1977 0.35 0.21 4.08 3.97 2.36 2.91 4.32 6.48 5.23 3.76 2.11 1.97 37.75 1978 1.28 0.50 1.44 5.14 4.85 3.65 8.56 3.09 7.90 1.64 2.58 3.13 43.76 1979 2.72 1.14 4.92 6.06 2.60 5.34 3.68 4.96 0.00 1.57 2.84 2.61 38.44 1980 1.22 1.12 1.51 3.26 2.70 3.20 3.81 7.86 9.02 1 2.89 0.94 2.24 1 39.77 1981 0.07 1.69 0.54 5.82 5.09 6.44 3.97 6.29 3.06 1.27 1.92 1.06 37.22 1982 2.64 0.77 3.82 3.25 3.64 2.96 6.34 1.94 1.30 2.17 5.01 5.87 39.71 1983 0.57 1.25 3.94 6.59 4.22 2.75 6.97 2.38 3.54 2.64 5.20 2.89 42.94 1984 0.59 2.49 2.76 4.02 4.12 5.78 1.83 0.94 4.92 1.99 3.72 2.22 35.38 20

PRECIPITATION (inches) AURORA, IL IL YEAR JAN FEB MAR APR MAY JUN JUL AUG SEP OCT NOV DEC ANN 1985 1.94 2.61 5.37 1.93 2.63 2.70 3.26 1.86 1.94 3.98 7.89 1.31 37.42 1986 0.49 2.44 1.12 1.75 3.23 4.19 3.25 1.67 1 7.08 1 3.23 2 1.36 1 0.97 1 30.78 1987 1.55 0.00 1.53 2.49 5.14 5.83 3.52 1 13.364.04 1.17 3.79 4.79 47.21 1988 1.53 0.97 2.39 3.18 1.86 0.95 3.40 4.18 1.94 3.23 5.04 2.33 31.00 1989 0.90 1.11 1.68 1.12 1.94 4.29 6.63 2.57 6.90 1.07 2.58 0.55 31.34 1990 2.88 3.14 3.34 2.01 1 8.00 6.31 4.41 5.08 1.38 5.55 5.54 2.15 49.79 1991 1.28 0.69 4.03 4.47 5.80 1.00 1.45 1.70 2.84 7.82 3.26 1.38 35.72 1992 0.92 1.04 2.75 3.31 0.75 2.22 4.45 2.48 8.26 1.22 6.70 3.03 37.13 1993 1.44 1.09 2.53 1 4.66 2.03 9.56 2.34 5.88 4.63 1.68 1.33 0.97 38.14 1994 2.11 2.46 0.33 1.98 1.57 6.03 2.46 7.05 1.57 1.35 6.28 2.52 35.71 1995 3.53 0.37 1.54 5.80 4.54 3.01 3.73 4.75 2.31 5.12 3.84 0.87 39.41 1 Elgin data substituted for Aurora 2 DeKalb data substituted for Aurora 3 Chicago-0'Hare AP data substituted for Aurora 4 Chicago-loop data substituted for Aurora 5 Marengo data substituted for Aurora SNOWFALL (inches) AURORA, IL YEAR JUL AUG SEP OCT NOV DEC JAN FEB MAR APR MAY JUN ANN 1900-01 8.1 17.0 4.3 1.0 0.0 0.0 1901-02 0.0 0.0 0.0 0.0 0.0 5.8 4.9 3.9 1.5 0.0 0.0 0.0-16.1 1902-03 0.0 0.0 0.0 0.0 0.8 4.3 5.4 10.0 2.1 0.0 0.0 0.0 22.6 1903-04 0.0 0.0 0.0 0.0 2.5 4.4 5.0 11.4 8.3 0.0 0.0 0.0 31.6 1904-05 0.0 0.0 0.0 0.0 0.0 8.3 9.3 13.4 6.0 0.0 0.0 0.0 37.0 1905-06 0.0 0.0 0.0 0.0 0.1 1.6 0.9 0.0 6.4 0.0 0.0 0.0 9.0 1906-07 0.0 0.0 0.0 0.0 0.0 0.5 8.6 2.6 1.2 1.0 1.3 0.0 15.2 1907-08 0.0 0.0 0.0 0.0 1.0 3.7 8.1 23.6 0.0 0.0 0.0 0.0 36.4 1908-09 0.0 0.0 0.0 0.0 0.0 3.0 3.0 0.0 2.5 0.9 0.0 0.0 9.4 1909-10 0.0 0.0 0.0 0.0 0.0 18.3 0.0 2.0 0.0 8.0 0.0 0.0 28.3 1910-11 0.0 0.0 0.0 0.0 0.0 6.5 0.0 9.0 2.8 2.5 0.0 0.0 20.8 1911-12 0.0 0.0 0.0 0.0 1.2 7.7 0.0 9.1 13.1 1.0 0.0 0.0 32.1 1912-13 0.0 0.0 0.0 0.0 0.0 0.0 5.7 5 10.0 5.0 0.0 0.0 0.0 20.7 1913-14 0.0 0.0 0.0 1.5 0.0 2.2 18.5 7.0 2.5 0.0 0.0 0.0 31.7 1914-15 0.0 0.0 0.0 0.0 0.0 18.5 14.5 2.5 3.5 0.0 0.0 0.0 39.0 1915-16 0.0 0.0 0.0 0.0 1.3 13.5 9.5 4.0 6.0 0.0 0.0 0.0 34.3 1916-17 0.0 0.0 0.0 0.0 0.5 12.0 6.7 3.0 0.0 0.0 0.0 0.0 22.2 1917-18 0.0 0.0 0.0 1.5 0.2 4.2 32.0 5.0 0.5 0.0 0.0 0.0 43.4 1918-19 0.0 0.0 0.0 0.0 0.0 5.0 2.5 7.5 8.5 0.0 0.0 0.0 23.5 1919-20 0.0 0.0 0.0 0.0 0.0 15.0 8.5 5 2.5 1.7 4.0 0.0 0.0 31.7 21